In one conventional sliding bearing, a bearing alloy layer of an Al--Sn alloy, an Al--Si--Sn alloy, a Cu--Pb alloy or a Cu--Pb--Sn alloy is formed on a surface of a steel support or backing metal. In another conventional sliding bearing, a coating layer is formed on a back surface of a backing metal to cope with fretting.
With a compact and lightweight design of recent internal combustion engines for fuel-saving purposes and also with a high output design thereof, the engine is used at a high temperature, high speed and a high load. Therefore, a close contact of the bearing portion with a housing fails to be maintained, so that damage of the bearing, such as fatigue and seizure due to fretting (which means a surface damage developing when a slight relative motion is periodically repeated between two contact surfaces), has frequently occurred. Particularly with respect to a connecting rod, not only the bearing but also the connecting rod itself may be subjected to fatigue failure. Therefore, whether or not the conventional sliding bearings has an anti-fretting property has become a major problem.
To overcome these problems, it has been proposed to improve the rigidity of the housing, or to increase an interference to enable the bearing to follow the deformation of the housing when mounting the bearing portion, or to form a film of Cu, Ni, Al or an alloy thereof, or a synthetic resin such as PTFE, polyamide and polyethylene, on a back surface of a back metal of the bearing so as to improve its compatibility with its mating material.